MUSCLES
Ch 10-11 Topics
*Important: See objectives for our focus!
Anatomy
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You must be able to identify and label the general
body musculature on p. 279 and p. 280. This is
important as it shows major muscles in the human body.
Expect to see this diagram on your test!
You must be able to label the sarcomere in box 11-1 on
p. 313. This is important when learning about the
contractile unit of the muscle cell.
You must be able to label the structure of the thin and
thick myofilament in figure 11-4 on p. 315 as this is
imperative to understanding the physiology of muscle
contraction.
Muscle Types
Attachment of Muscles
The origin is fixed. Insertion can
move.
Muscles work as antagonists and act
by contracting the insertion to the
origin .
Muscle contraction is very important
for this unit. We will spend several
slides learning this sequence.
Naming Muscles
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Location (ex: gluteus muscle)
Function (ex: adductor—will adduct leg to midline
of body)
Shape (ex: deltoid- triangle shape)
Direction of Fibers (ex: rectus---means straight)
Number of heads/divisions (ex: sternocleidomastoid
has sternum and clavicle as origin and mastoid as
insert
Size (ex: gluteus maximus vs. gluteus minimus)
Muscle Arrangement
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Muscle fibers are arranged differently in different
muscles depending on function.
Spincter (circular)- open in center.
Convergent- Converge at insertion.
Parallel- run parallel and can contract
a great distance.
Pennate- many fibers in condensed
area. Can be unipennate, bipennate,
or multipennate.
General Function of Muscles
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MOVEMENT
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HEAT PRODUCTION
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POSTURE
Muscle Contraction Animation
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http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter1
0/animation__action_potentials_and_muscle_contracti
on.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter1
0/animation__breakdown_of_atp_and_crossbridge_movement_during_muscle_contraction.html
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter1
0/animation__myofilament_contraction.html
Sarcomere Contraction Animation
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http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapte
r10/animation__sarcomere_contraction.html
Important to Understand
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SR= sarcoplasmic reticulum- This holds and releases calcium
for muscle contraction.
THIN myofilament is ACTIN. Actin binds to…
THICK myofilament which is MYOSIN.
TROPOMYOSIN and TROPONIN block the binding sites on
the actin so myosin can’t bind. They will shift in response to
calcium release.
ATP makes it all possible
Let’s Put the Following in Order
PS- These are out of order!!!
A)
B)
C)
D)
E)
F)
Energized myosin crosses bridges of the thick myofilaments
bind to actin and use their energy to pull thin myofilaments
toward the center of each sarcomere. Repeats as long as ATP
is available.
Ca+ is released from the SR into the sarcoplasm where it
binds to troponin in thin myofilaments.
Nerve impulse reaches end of motor neuron, releasing
acetylcholine.
As the thin filaments slide past thick myofilaments, the entire
muscle fiber shortens.
Troponin and tropomyosin shift, exposing actin binding sites.
Acetylcholine diffuses and binds to acetycholine receptors in
muscle fibers.
Aerobic vs. Anaerobic Respiration
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Which one requires
oxygen?
Which one is short term?
Which one causes a
byproduct of lactic acid?
Where do each take place?
Which one makes the most
ATP?
Slow vs. Fast vs. Intermediate Fibers
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Slow fibers are also called RED fibers because they
contain a high concentration of myoglobin (reddish
pigment that stores oxygen). Their myosin acts at a SLOW
rate yet can avoid fatigue. What kind of muscles may this
be useful for?
Fast fibers are also called WHITE fibers as there is a low
concentration of myoglobin. Their myosin works faster
because Ca+ is delivered faster by their SR. But ATP is
depleted fast and so this is a short duration. What kind of
muscles in your body would be suited for this?
Intermediate fibers fall in between.
How do these differ in athletes?
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Your book has some great graphs showing
differences in concentrations of muscle types. (p.
320)
PubMed, the U.S. National Library of Medicine,
reports studies done observing athletes and fiber
differences.
Example:
http://www.ncbi.nlm.nih.gov/pubmed/18535124?it
ool=EntrezSystem2.PEntrez.Pubmed.Pubmed_Results
Panel.Pubmed_RVDocSum&ordinalpos=12
Muscle Fatigue
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Physiologically, this would be caused by a lack of what
energy molecule?
If you lack this energy molecule, think about what would
not be able to result?
Lacking this energy molecule would mean that a
depletion of oxygen and/or glucose in muscle fibers may
be present. What byproduct can occur if oxygen is
lacking?
Psychological fatigue will produce the feeling that usually
stops us from continuing muscular activity but
physiological fatigue would prevent an actual contraction.
Effects of Exercise on Skeletal
Muscle
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Prolonged inactivity causes disuse atrophy
Muscle hypertrophy is enhanced by strength training since
muscles are given heavy resistance training. This can
increase the number of myofilaments in each muscle fiber.
This can increase the mass of the muscle.
Endurance training (aka aerobic training) does NOT result in
hypertrophy but it increases the number of blood vessels in
the muscle without increasing its size. More blood vessels can
allow better delivery of oxygen and glucose. Also aerobic
training can cause an increase in the number of mitochondria
which would produce more of what energy molecule?
Abnormal Muscle Contractions
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Cramps- involuntary muscle spasms. Often a muscle
is inflamed but it can also be a symptom of
irritation or ion/water imbalance.
Convulsions- Abnormal, uncoordinated tetanic
contractions. Disturbances in the brain can cause
output along motor nerves to be irregular and
disorganized.
Fibrillation- abnormal contraction where individual
fibers do not contract at the same time. Produces
flutter but no movement. Can occur in cardiac
muscle.
Diagram of Actin and Myosin
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Take a look at p. 315. It has pictures of actin and
myosin. I want you to diagram the myosin head and
its ability to bind to actin.
You need to be able to explain the order of
contraction, as I will ask EACH person in the group a
part of the sequence. You are not done until your
entire group answers it correctly.
Not shown in picture, but I want you to include is
calcium (what does it do?) and ATP.
Trapezius
Superior extensor retinaculum
Soleus
Gastrocnemius
Pectoralis major
Peroneus longus
Sternocleiodomastoid
Peroneus brevis
Patellar Tendon
Peroneus longus
Soleus
Calcaneal tendon
Peroneus brevis
Gastrocnemius
Sternocleidomastoid
Splenius capitis